Coffee compositions can be provided to a coffee consumer in several different forms. Some consumers prefer to be provided with whole roasted coffee beans, which they grind themselves immediately before brewing. Other consumers find it more convenient to be provided with pre-ground roasted coffee, which they then brew. Other consumers prefer using instant coffee.
Some ground coffee compositions contain not only the ground coffee but also additional components. For example, U.S. Pat. No. 6,841,185 describes how a flavouring component can be added to, for example, ground coffee. Other additional ingredients may also be added, including creamers, aroma enhancers, sweeteners and thickeners. In U.S. Pat. No. 6,841,185, the flavouring component and the additional ingredients are mixed with the ground coffee by conventional mixing by allowing the coffee and flavouring particles to tumble over each other.
One problem of providing a coffee composition containing more than just a single coffee component is that, over time, the individual components of the coffee composition segregate and separate from one another. As a result, when the coffee composition is placed in a container and allowed to settle, small components or denser components group together at the bottom of the container while larger or less dense components group together at the top of the container. For example, some components added to a coffee composition are smaller in size than the coffee component of the composition. Thus, an end consumer can experience either an increased concentration of, for example, flavour component or a reduced concentration of the flavour component according to whether the coffee originates from the top or the bottom of the container in which the composition is contained.
U.S. Pat. No. 6,841,185 describes two possible solutions to the problem of segregation. The first solution involves using agglomerated flavouring ingredients so that the size of the flavouring ingredient becomes similar to the size of the coffee in the coffee composition, thereby reducing segregation. The second solution involves using a specific ratio of the sizes of particles of the coffee component to the size of the flavouring component and reportedly controlling the van der Waals interaction between the two components to prevent segregation.
One specific additional component that can be added to ground coffee is instant coffee powder. For example, in EP 0928561, instant coffee powder is added to a ground coffee to decrease the brew time of the coffee composition so that coffee can be made in a vending machine more quickly while maintaining some of the preferred flavour of the ground coffee in the coffee brew. As further examples, EP 0220889, GB 2006603, GB 0229920, U.S. Pat. No. 3,261,689 and U.S. Pat. No. 3,713,842 describe a mixture of ground coffee and instant coffee in which the ground coffee is contacted with a dissolved, aqueous instant coffee, for example by spraying. In U.S. Pat. No. 3,261,689, the spraying is said not to result in agglomeration of the coffee grounds, whereas in U.S. Pat. No. 3,713,842, the spraying is used to purposefully cause agglomeration. Separately, U.S. Pat. No. 2,278,473 suggests the impregnation of exploded coffee particles with molten cane sugar.